It depends on what your goals are. I'm a C#/Javascript developer myself and I have tried to start a few side projects using new technologies in the past, but I

It depends on what your goals are. I'm a C#/Javascript developer myself and I have tried to start a few side projects using new technologies in the past, but I noticed that I spent a lot of time fighting with the new framework/platform instead of solving whatever problem I was trying to solve. So I decided to double down on C#/Javascript and put my efforts into building products using what I already knew. I'm glad I did because one of these side projects turned into a healthy business, which will likely enable me to "retire" in a couple of years. I think that if your goal is to solve problems, leverage what you already know. If your goal is to be more employable and improve at your craft, learning new languages should help you.